Various types of object detection systems for motor vehicles have been developed which utilize one or more sensors to identify, interpret and/or locate objects surrounding the vehicle. Examples of such systems include forward looking systems (FLS), rear detection systems (RDS), and side detection systems (SDS).
Some FLSs are referred to as “vision-only systems,” in that they only utilize cameras and not radar, laser or other types of sensors. In the case of single camera vision systems (referred to as “monocular vision systems”) and multiple camera vision systems (referred to as “stereo vision system”) a processing unit usually has to estimate the pan and tilt angles of a camera, as well as the vertical curvature of an upcoming road segment in order to accurately interpret and locate detected objects. One way in which these estimates can be performed is by using optical flow techniques in which a focus of expansion is found in the image. These techniques, however, require a significant amount of computations and frequently do not produce robust, accurate estimates.
Another type of object detection system is referred to as a “radar-cued vision system”, which broadly includes all object detection systems that utilize both radar sensors and cameras to identify, interpret and/or locate objects. A typical forward looking, radar-cued vision system for a vehicle includes a radar sensor and one or more cameras directed generally in front of the vehicle. The radar sensor initially detects an object so that a region of the camera image in which the object is likely to be found can be identified, narrowed in on, and analyzed in more detail.